Identified first by comidienne Margaret Cho, disaster nudity is the semi-clothed state where one is wearing only a shirt, or only a coat, or is missing pants or underwear. It is called "disaster nudity" because it looks like one was "in the shower and there was an earthquake," so one just had to throw on what was readily available.

Girl: Oh mylanta, I'm so tired of my boyfriend walking around in just a t-shirt. No one wants to see flaccid man junk that early in the morning. Or when they're making toast.
Girl's Friend: Wow. Sounds like Disaster Nudity to me. You gotta have a talk with that fashion-challenged dbag.